I have a friend who sucks the air out of the room whenever he comes around. He is so blustery and self-absorbed that people don’t interact with him; they capitulate. I also have friends who by their mere presence light up the room, raising the spirits of everyone gathered. I know people who cast a pall over the group and drag it down; others who have a calming effect on gatherings.

These are all caricatures, of course. Nobody can sway the emotions of an entire room, energizing or subduing or infuriating every member of the group. After all, each of us has his or her own emotional make-up, which is surely more powerful than the mere presence of another person. A roomful is not a human entity, with collective emotions.

Or is it? It may be humbling to know, but new research suggests that there may be some truth to these caricatures. Each of us is autonomous, of course, with temperament and personality, but some people may have a powerful emotional presence that can indeed influence the feeling of an entire room.

That’s the idea being explored by two business professors, Noah Eisenkraft of Penn and Hillary Anger Elfenbein of Washington University in St. Louis. The scientists wanted to explore this phenomenon with naturally occurring groups, so they recruited an entire class of first-year MBA students. These 239 students were randomly assigned to work groups, most made up of five students, which were diverse for nationality, gender, and work experience. The group members took all the same classes, worked on group projects, and even socialized frequently outside class. In other words, they spent a lot of time in the same room.

The idea was to track these group members’ emotions—and emotional interactions—over an entire semester. So the scientists gave a personality test to start, then after the groups had worked together for a month, they questioned each member about both positive and negative feelings they experienced for each of the other group members—boredom, stress, anger, enthusiasm, and so forth. They also observed the networks that formed over the semester, to see if any one group member was becoming the emotional center of the group.

The results were mixed and intriguing. The students’ upbeat emotions were largely accounted for by individual emotional make-up—but not entirely. The presence of others also shaped the students’ feelings, with the most dominant group members having the most power to lift others’ spirits. But the big surprise came with negative emotions like sadness and anger. As reported on-line this week in the journal Psychological Science, downbeat emotions were shaped more by others than by individual temperament, and these effects were traceable to individuals with the most extraverted and disagreeable personalities. Importantly, the scientists ruled out emotional “contagion” as an explanation for the phenomenon: It’s not simply that miserable people were dragging others down with them, but something about them was affecting the entire room in the same way—and not in a good way.

We usually call these people “bad apples.” But if we’re not simply “catching” their bad vibes, what is happening? It’s not entirely clear, the scientists say. It could be that people with an emotional “presence” express themselves differently—with most body-language, for example—or they may convey dominance or warmth or creepiness in very subtle ways.

Excerpts from “We’re Only Human” appear regularly in the magazine Scientific American Mind. Wray Herbert’s book, On Second Thought, will be published by Crown in September.